Unlike citizens in nearly all other democracies, most U.S. citizens bear the respon- sibility for registering to vote. We test whether states can help citizens overcome the barriers to registration and turnout using a simple postcard. To do this, we leverage a new program that brings states together to improve the quality of their voter reg- istration rolls and generate lists of eligible but unregistered citizens. Using a unique list of eligible but unregistered citizens from the Pennsylvania Department of Trans- portation, we partnered with the Pennsylvania Department of State’s Office to con- duct a large-scale voter registration field experiment prior to the 2016 election. We provide new tests of traditional theories related to lowering the costs of registration as well as new theories related to promoting government responsiveness. We find that contact in the form of a single postcard from the Department of State led to a one percentage point increase in registration and a 0.9-point increase in turnout, regardless of the content of the postcard. Registration effects were strongest among young, first-time voters. Importantly, new registrants voted at a rate far exceeding rates found in previous registration drives.